Visit Settings → Email → Snippets (/settings/email/snippets). Each snippet has a name (e.g., “Intro paragraph”), a shortcut (e.g., intro), and a body (HTML allowed). Pick a scope: Just me for a private snippet, or Whole org to share with the team.

• Shortcuts are 1–32 chars, lowercase letters + digits + _ + -.
• Body is up to 16,000 chars; can include simple HTML formatting.
• Org-shared snippets show with an “Org-shared” tag in the list.

In any compose textarea (full compose, floating compose, inline reply), type ;followed by the shortcut and a trailing space (or Enter / Tab). The trigger replaces with the snippet's body and leaves your cursor at the end. The trigger character must be at the start of the line, after whitespace, or after punctuation — emoticons like ;) stay safe.